CN107123653B

CN107123653B - Semiconductor device with a plurality of semiconductor chips

Info

Publication number: CN107123653B
Application number: CN201710363003.5A
Authority: CN
Inventors: 坂仓真之; 后藤裕吾; 三宅博之; 黑崎大辅
Original assignee: Semiconductor Energy Laboratory Co Ltd
Current assignee: Semiconductor Energy Laboratory Co Ltd
Priority date: 2011-10-07
Filing date: 2012-10-08
Publication date: 2022-02-11
Anticipated expiration: 2032-10-08
Also published as: KR20210134538A; TW201707208A; KR20220053528A; TW201947669A; JP2022051730A; KR102011257B1; KR20230095890A; KR20200043339A; KR20200088250A; US10431318B2; JP7623546B1; KR102599914B1; CN103035192A; TW201842591A; JP2013093565A; KR20210070960A; US20130088468A1; US11133078B2; DE102012218310A1; US20230395172A1

Abstract

semiconductor device. One aspect of the present invention provides a semiconductor device capable of preventing a decrease in yield due to electrostatic breakdown, wherein a scan line driver circuit that supplies a signal for selecting a plurality of pixels to a scan line includes a shift register that generates the signal and, in the above-mentioned shift register, one conductive film serving as a gate electrode of a plurality of transistors is divided into a plurality of pieces, and the above-mentioned divided conductive films are formed into a plurality of conductive films by a conductive film formed in a layer different from the above-mentioned divided conductive film. The membranes are electrically connected to each other. The plurality of transistors described above include transistors on the output side of the shift register.

Description

Semiconductor device with a plurality of semiconductor chips

The present application is a divisional application of an invention patent application having an application date of 2012, 10/8, an application number of 201210378806.5 and an invention name of "semiconductor device".

Technical Field

The present invention relates to a semiconductor device using an insulated gate field effect transistor.

Background

In recent years, as a novel semiconductor material having both high mobility of polycrystalline silicon or microcrystalline silicon and uniform device characteristics of amorphous silicon, a metal oxide which exhibits semiconductor characteristics and is called an oxide semiconductor has been attracting attention. Metal oxides are used for various purposes, and for example, indium oxide, which is a well-known metal oxide, is used for a transparent electrode material in a liquid crystal display device or the like. As a metal oxide exhibiting semiconductor characteristics, for example, tungsten oxide, tin oxide, indium oxide, zinc oxide, and the like are known, and a transistor in which the metal oxide exhibiting semiconductor characteristics is used for a channel formation region is known (patent documents 1 and 2).

[ patent document 1] Japanese patent application laid-open No. 2007-123861

[ patent document 2] Japanese patent application laid-open No. 2007-96055

Since a semiconductor display device including transistors including amorphous silicon or oxide semiconductor can correspond to a glass substrate of fifth generation (1200 mm in the lateral direction × 1300mm in the vertical direction) or more, there are advantages of high productivity and low cost. When the panel is increased in size, a load on wiring called a bus line connected to a plurality of pixels, for example, a scan line, a signal line, and the like, is increased in a pixel portion of the semiconductor display device. Therefore, a driving circuit for supplying potentials to a scanning line and a signal line requires high current supply capability, and thus tends to be as follows: as the panel becomes larger, the size of a transistor constituting a driver circuit, particularly a transistor located on the output side, increases according to its electrical characteristics.

When the size of the above-described transistor increases, the area of a wiring used as a gate electrode of the transistor in the driver circuit increases due to a layout relationship. Therefore, a phenomenon in which charges are accumulated in the wiring in a manufacturing process using plasma such as dry etching is likely to occur, and the probability of electrostatic damage of the wiring due to the discharge of the charges accumulated in the wiring is increased.

In particular, the on current of a transistor having amorphous silicon or an oxide semiconductor tends to be smaller than that of a transistor using polycrystalline silicon or single crystal silicon. When a transistor including amorphous silicon or an oxide semiconductor is used, a panel can be increased in size in terms of process, but in order to satisfy the current supply capability of a driver circuit, a transistor having a larger size needs to be designed. Therefore, the probability of electrostatic breakdown of the wiring due to an increase in the area of the wiring is increased, and the yield is likely to be lowered.

Disclosure of Invention

In view of the above background, it is an object of the present invention to provide a semiconductor device capable of preventing a decrease in yield due to electrostatic breakdown.

In one embodiment of the present invention, one conductive film serving as gate electrodes of a plurality of transistors is divided into a plurality of portions in order to prevent charges from being accumulated in the conductive film due to an antenna effect. The divided conductive films are separated. The divided conductive films are electrically connected to each other by a conductive film different from the divided conductive films. The plurality of transistors include a transistor on the output side of the driver circuit.

Alternatively, in one embodiment of the present invention, a scanning line driver circuit which supplies signals for selecting a plurality of pixels to a scanning line includes a shift register which generates the signals, and one conductive film which is used as gate electrodes of a plurality of transistors in the shift register is divided into a plurality of conductive films. The divided conductive films are separated. The divided conductive films are electrically connected to each other by a conductive film different from the divided conductive films. The plurality of transistors include a transistor on the output side of the shift register.

The conductive film different from the divided conductive film may be provided in a layer different from the divided conductive film. Further, the conductive film formed in a layer different from the divided conductive films may be formed in the same layer as the source and drain electrodes of the plurality of transistors.

In one embodiment of the present invention, the plurality of transistors may include amorphous silicon or an oxide semiconductor in an active layer.

In one embodiment of the present invention, by electrically connecting a plurality of conductive films functioning as gate electrodes to each other by conductive films formed in different layers, the area of each conductive film functioning as a gate electrode can be suppressed to be smaller than that in the case where one conductive film is used as a plurality of gate electrodes. Accordingly, even if the size of the transistor on the output side of the driver circuit increases due to an increase in the size of the panel, the area of the conductive film serving as the gate electrode of the transistor can be reduced, and thus electrostatic damage of the conductive film due to the antenna effect can be prevented in a manufacturing process using plasma, such as a process of forming the gate electrode by etching.

Specifically, a semiconductor device according to one embodiment of the present invention includes a driver circuit which supplies signals to a plurality of pixels. The driver circuit includes a plurality of transistors, and a gate electrode of at least one transistor on a signal output side and a gate electrode of at least one transistor other than the transistor on the output side among the plurality of transistors are electrically connected by a conductive film different from the gate electrode.

In the semiconductor device according to one embodiment of the present invention, the above structure can prevent a decrease in yield due to electrostatic breakdown.

Drawings

Fig. 1 is a diagram showing the structure of a semiconductor device of the present invention;

FIGS. 2A to 2C are top and cross-sectional views of a transistor;

FIGS. 3A to 3C are top and cross-sectional views of a transistor;

fig. 4 is a circuit diagram showing the structure of a semiconductor device of the present invention;

fig. 5 is a diagram showing the structure of a shift register;

fig. 6 is a timing chart showing the operation of the pulse output circuit;

fig. 7 is a diagram schematically showing a j-th pulse generating circuit;

fig. 8A and 8B are diagrams showing the structure of a pulse generating circuit;

fig. 9A and 9B are diagrams showing the structure of a pulse generating circuit;

fig. 10 is a diagram showing the structure of a pulse generating circuit;

fig. 11 is a cross-sectional view of a driver circuit and a pixel;

fig. 12 is a diagram showing the structure of a panel;

fig. 13A to 13E are diagrams of electronic devices.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the following description, and those skilled in the art can easily understand that the mode and details thereof can be changed into various forms without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments shown below.

Note that all semiconductor devices using a transistor such as an integrated circuit, an RF tag, a semiconductor display device, or the like are included in the scope of the present invention. Further, the Integrated Circuit includes, in its category, an LSI (Large Scale Integrated Circuit) including a microprocessor, an image processing Circuit, a DSP (Digital Signal Processor), a microcontroller, or the like, and a Programmable Logic Device (PLD) such as an FPGA (Field Programmable Gate Array) and a CPLD (Complex PLD: Complex Programmable Logic Device). Further, semiconductor display devices in which a circuit element including a semiconductor film is included in a driver circuit, such as a liquid crystal display device, a light-emitting device provided with a light-emitting element typified by an organic light-emitting element (OLED) in each pixel, electronic paper, a DMD: (Digital micro mirror Device: Digital Micromirror Device), PDP (Plasma Display Panel: Plasma Display Panel), FED (Field Emission Display: Field Emission Display), and the like.

Note that the semiconductor display device in this specification includes within its scope: a panel in which a display element such as a liquid crystal element or a light-emitting element is formed in each pixel; and a module in which an IC or the like including a controller is mounted on the panel.

Embodiment mode 1

Fig. 1 shows an example of a circuit configuration of a semiconductor device according to one embodiment of the present invention. The semiconductor device 100 shown in fig. 1 includes a plurality of transistors including at least a transistor 101 and a transistor 102.

The semiconductor device 100 is supplied with a high-level potential VH or a low-level potential VL through the wiring 105 and the wiring 106. Fig. 1 illustrates a case where the potential VH is supplied to the semiconductor device 100 through the wiring 105, and the potential VL is supplied to the semiconductor device 100 through the wiring 106. Further, the potential Vin of the input signal is supplied to the semiconductor device 100 through the wiring 103. In the semiconductor device 100, a plurality of transistors including the transistor 101 and the transistor 102 are switched in accordance with the potential Vin. By performing the switching, one of the potential VH and the potential VL is selected, and the selected potential is output from the semiconductor device 100 through the wiring 104 as the potential Vout of the output signal.

In the transistor 102, one of a source terminal and a drain terminal is connected to a wiring 104. That is, the transistor 102 is located on the output side of the semiconductor device 100 and has a function of controlling output of the potential Vout to the wiring 104. In one embodiment of the present invention, a gate electrode (G) of the transistor 101 and a gate electrode (G) of the transistor 102 are electrically connected to each other through a wiring 107 which is different from the gate electrode.

Note that in this specification, "connected" means both electrically connected and directly connected without any particular description and corresponds to a state in which current, voltage, or potential can be supplied or transmitted. Therefore, "connected state" does not necessarily mean a state of direct connection, and includes, in the category of "connected state", a state of indirect connection through an element such as a wiring, a conductive film, a resistor, a diode, or a transistor so that current, voltage, or potential can be supplied or transmitted.

The "source terminal of the transistor" refers to a source region corresponding to a part of the active layer or a source electrode connected to the active layer. Similarly, the "drain terminal of the transistor" refers to a drain region of a part of the active layer or a drain electrode connected to the active layer.

The names of the source terminal and the drain terminal of the transistor are interchanged according to the polarity of the transistor and the level of the potential supplied to each electrode. In general, in an n-channel transistor, an electrode to which a low potential is supplied is referred to as a source terminal, and an electrode to which a high potential is supplied is referred to as a drain terminal. In the p-channel transistor, an electrode to which a low potential is supplied is referred to as a drain terminal, and an electrode to which a high potential is supplied is referred to as a source terminal. In this specification, the connection relationship of the transistors is explained assuming that the source terminal and the drain terminal are fixed in some cases for convenience, but in reality, the names of the source terminal and the drain terminal are interchanged in accordance with the above potential relationship.

In addition, when a potential Vout output from the semiconductor device 100 is supplied to a wiring having a large load called a bus line connected to a plurality of pixels, such as a scan line or a signal line, the transistor 102 which controls the output of the potential Vout is required to have a large current supply capability. Therefore, it is preferable to design the transistor 102 so that the channel width W is larger than the channel width W of the transistor 101.

Fig. 2A shows a top view of the transistor 101 and the transistor 102 shown in fig. 1 as an example. However, in fig. 2A, a plan view in which the gate insulating film 111 is omitted is shown in order to clearly show the layout of the

transistors

101 and 102. Further, fig. 2B shows an example of a cross-sectional view of the transistor 102 shown in fig. 2A along a chain line a1-a 2.

In fig. 2A, a transistor 101 includes: a conductive film 110 serving as a gate electrode; a gate insulating film 111 over the conductive film 110; a semiconductor film 112 provided over the gate insulating film 111 at a position overlapping with the conductive film 110; and a conductive film 113 and a conductive film 114 which function as a source electrode or a drain electrode over the semiconductor film 112.

Further, in fig. 2A and 2B, the transistor 102 includes: a conductive film 115 serving as a gate electrode; a gate insulating film 111 over the conductive film 115; a semiconductor film 116 provided over the gate insulating film 111 at a position overlapping with the conductive film 115; and a conductive film 117 and a conductive film 118 which function as a source electrode or a drain electrode over the semiconductor film 116.

In one embodiment of the present invention, the current supply capability of the transistor 102 on the output side is higher than the current supply capability of the transistor 101. Therefore, in one embodiment of the present invention, as shown in fig. 2A, it is preferable that the channel width W of the transistor 102 be set to be smaller than that of the transistor 102₁₀₂And channel length L₁₀₂The ratio therebetween is set to be larger than the channel width W of the transistor 101₁₀₁And channel length L₁₀₁The ratio between them is large. Specifically, the channel width W₁₀₂And channel length L₁₀₂Preferably the ratio between the channel width W and the channel width W₁₀₁And channel length L₁₀₁More preferably three times or more, of the ratio therebetween.

Further, the conductive film 110 and the conductive film 115 are separated. Note that in this specification, separation means a case where separation occurs physically. Further, in fig. 2A and 2B, the conductive film 110 and the conductive film 115 are electrically connected through a conductive film 119 serving as a wiring. Specifically, the conductive film 110 and the conductive film 115 are connected to the conductive film 119 through an opening 120 and an opening 121 formed in the gate insulating film 111.

Further, the conductive film 110 and the conductive film 115 shown in fig. 2A and 2B can be formed by processing one conductive film formed over an insulating surface into a desired shape by etching or the like. The

conductive films

113 and 114, the

conductive films

117 and 118, and the conductive film 119 can be formed by processing one conductive film formed over the gate insulating film 111 so as to cover the

openings

120 and 121 into a desired shape by etching or the like. That is, the conductive film 119 is formed in a layer different from the

conductive films

110 and 115.

As shown in fig. 2A and 2B, in one embodiment of the present invention, the conductive film 110 and the conductive film 115 which function as gate electrodes are electrically connected to each other by the conductive film 119 formed in a layer different from the conductive film 110 and the conductive film 115.

As a comparative example, fig. 2C shows another example of a top view of the transistor 101 and the transistor 102 shown in fig. 1. However, in fig. 2C, a plan view in which the gate insulating film is omitted is shown in order to clearly show the layout of the

transistors

101 and 102.

In fig. 2C, the transistor 101 includes: a conductive film 122 functioning as a gate electrode; a gate insulating film over the conductive film 122; a semiconductor film 123 provided over the gate insulating film at a position overlapping with the conductive film 122; and a conductive film 124 and a conductive film 125 functioning as a source electrode or a drain electrode over the semiconductor film 123.

Further, in fig. 2C, the transistor 102 includes: a conductive film 122 functioning as a gate electrode; a gate insulating film over the conductive film 122; a semiconductor film 126 provided over the gate insulating film at a position overlapping with the conductive film 122; and a conductive film 127 and a conductive film 128 functioning as a source electrode or a drain electrode over the semiconductor film 126.

In other words, in fig. 2C, the transistor 101 and the transistor 102 commonly use the conductive film 122, and the conductive film 122 functions as a gate electrode of the transistor 101 and a gate electrode of the transistor 102. Therefore, in fig. 2C, the area of the conductive film 122 functioning as a gate electrode is larger than the area of the conductive film 110 and the area of the conductive film 115 functioning as gate electrodes in fig. 2A and 2B.

Thus, in one embodiment of the present invention, the area of the conductive film 110 and the area of the conductive film 115 which serve as gate electrodes can be reduced to be smaller than the area of the conductive film 122 in the comparative example, and therefore, when the

conductive films

110 and 115 are manufactured by etching, the amount of electric charges accumulated in the

conductive films

110 and 115 can be reduced, that is, the antenna effect can be reduced. Therefore, in one embodiment of the present invention, when the conductive film 110 and the conductive film 115 are manufactured by etching, electrostatic damage to the conductive film 110 and the conductive film 115 due to the discharge of the electric charges can be less likely to occur than in the comparative example.

In addition, in one embodiment of the present invention, when the

semiconductor films

112 and 116 over the

conductive films

110 and 115 are manufactured by etching, electrostatic breakdown of the

conductive films

110 and 115 due to an antenna effect is less likely to occur.

Next, fig. 3A shows an example of a top view of the transistor 101 and the transistor 102 shown in fig. 1, which is different from the top view shown in fig. 2A. However, in fig. 3A, a plan view in which the gate insulating film 211 is omitted is shown in order to clearly show the layout of the transistor 101 and the transistor 102. Further, fig. 3B shows an example of a cross-sectional view of the transistor 102 shown in fig. 3A along a chain line B1-B2.

In fig. 3A, a transistor 101 includes: a conductive film 213 and a conductive film 214 which function as a source electrode or a drain electrode; a semiconductor film 212 over the conductive film 213 and the conductive film 214; a gate insulating film 211 over the semiconductor film 212; and a conductive film 210 serving as a gate electrode provided over the gate insulating film 211 at a position overlapping with the semiconductor film 212.

Further, in fig. 3A and 3B, the transistor 102 includes: a conductive film 217 and a conductive film 218 which function as a source electrode or a drain electrode; a semiconductor film 216 over the conductive film 217 and the conductive film 218; a gate insulating film 211 over the semiconductor film 216; and a conductive film 215 serving as a gate electrode provided over the gate insulating film 211 at a position overlapping with the semiconductor film 216.

In one embodiment of the present invention, the current supply capability of the transistor 102 on the output side is higher than the current supply capability of the transistor 101. Therefore, in one embodiment of the present invention, as shown in fig. 3A, it is preferable that the channel width W of the transistor 102 be set to be smaller₁₀₂And channel length L₁₀₂The ratio therebetween is set to be larger than the channel width W of the transistor 101₁₀₁And channel length L₁₀₁The ratio between them is large. Specifically, the channel width W₁₀₂And channel length L₁₀₂Preferably the ratio between the channel width W and the channel width W₁₀₁And channel length L₁₀₁More preferably three times or more, of the ratio therebetween.

Further, the conductive film 210 and the conductive film 215 are separated. Further, in fig. 3A and 3B, the conductive film 210 and the conductive film 215 are electrically connected to each other through a conductive film 219 serving as a wiring. Specifically, the conductive film 210 and the conductive film 215 are connected to the conductive film 219 through an opening portion 220 and an opening portion 221 formed in the gate insulating film 211.

Further, the conductive film 210 and the conductive film 215 shown in fig. 3A and 3B can be formed by processing one conductive film formed over the gate insulating film 211 so as to cover the opening

portions

220 and 221 into a desired shape by etching or the like. The

conductive films

213 and 214, the

conductive films

217 and 218, and the conductive film 219 can be formed by processing one conductive film formed over an insulating surface into a desired shape by etching or the like. That is, the conductive film 219 is formed in a layer different from the

conductive films

210 and 215.

As shown in fig. 3A and 3B, in one embodiment of the present invention, the conductive film 210 and the conductive film 215 which are used as gate electrodes are electrically connected to each other by the conductive film 219 formed in a layer different from the conductive film 210 and the conductive film 215.

As a comparative example, fig. 3C shows another example of a top view of the transistor 101 and the transistor 102 shown in fig. 1. However, in fig. 3C, a plan view in which the gate insulating film is omitted is shown in order to clearly show the layout of the

transistors

101 and 102.

In fig. 3C, the transistor 101 includes: a conductive film 224 and a conductive film 225 functioning as a source electrode or a drain electrode; a semiconductor film 223 over the conductive film 224 and the conductive film 225; a gate insulating film over the semiconductor film 223; and a conductive film 222 serving as a gate electrode provided over the gate insulating film at a position overlapping with the semiconductor film 223.

Further, in fig. 3C, the transistor 102 includes: a conductive film 227 and a conductive film 228 functioning as a source electrode or a drain electrode; a semiconductor film 226 over the conductive film 227 and the conductive film 228; a gate insulating film over the semiconductor film 226; and a conductive film 222 functioning as a gate electrode provided over the gate insulating film at a position overlapping with the semiconductor film 226.

In other words, in fig. 3C, the conductive film 222 is used in common for the transistor 101 and the transistor 102, and the conductive film 222 functions as a gate electrode of the transistor 101 and a gate electrode of the transistor 102. Therefore, in fig. 3C, the area of the conductive film 222 functioning as a gate electrode is larger than the area of the conductive film 210 and the area of the conductive film 215 functioning as gate electrodes in fig. 3A and 3B.

Thus, in one embodiment of the present invention, the area of the conductive film 210 and the area of the conductive film 215 which serve as gate electrodes can be reduced to be smaller than the area of the conductive film 222 in the comparative example, and therefore, when the conductive film 210 and the conductive film 215 are manufactured by etching, the amount of electric charges accumulated in the conductive film 210 and the conductive film 215 can be reduced, that is, the antenna effect can be reduced. Therefore, in one embodiment of the present invention, when the conductive film 210 and the conductive film 215 are manufactured by etching, electrostatic damage to the conductive film 210 and the conductive film 215 due to the discharge of the electric charges can be less likely to occur than in the comparative example.

In addition, in one embodiment of the present invention, when various conductive films on the conductive film 210 and the conductive film 215 are processed into a desired shape by etching, electrostatic damage to the conductive film 210 and the conductive film 215 due to an antenna effect may not be easily generated.

Next, a structure of a pulse generating circuit in one of semiconductor devices according to one embodiment of the present invention will be described. Fig. 4 shows an example of a pulse generation circuit included in a semiconductor device according to one embodiment of the present invention.

The pulse generation circuit 300 shown in fig. 4 includes transistors 301 to 315 and a capacitor element 316. The transistor 302 corresponds to the transistor 101 shown in fig. 1. The transistor 309, the transistor 312, or the transistor 315 corresponds to the transistor 102 shown in fig. 1. Further, the pulse generating circuit 300 has a structure in which various potentials are supplied from the wiring 317 to the wiring 326 and potentials are output to the wirings 327 to 329.

By connecting the pulse generating circuits 300 of a plurality of stages, a shift register can be configured.

Specifically, when the transistors 301 to 315 are of an n-channel type, the potential VDD of a high level is supplied to the wiring 317, the potential VSS of a low level is supplied to the wiring 318, and the potential VEE of a low level is supplied to the wiring 326. The potential VEE is preferably the same as or higher than the potential VSS. Further, a potential LIN is supplied to the wiring 319, a potential INRES is supplied to the wiring 320, a potential CLK2 is supplied to the wiring 321, a potential RIN is supplied to the wiring 322, a potential CLK1 is supplied to the wiring 323, a potential PWC2 is supplied to the wiring 324, and a potential PWC1 is supplied to the wiring 325.

Further, the potential GOUT1 output from the pulse generating circuit 300 is supplied to the wiring 327. The potential GOUT2 output from the pulse generation circuit 300 is supplied to the wiring 328. The potential SROUT output from the pulse generating circuit 300 is supplied to the wiring 329.

The potential LIN, the potential RIN, the potential CLK2, and the potential INRES correspond to the potential Vin in the semiconductor device 100 shown in fig. 1. The potential GOUT1, the potential GOUT2, and the potential SROUT correspond to the potential Vout in the semiconductor device 100 shown in fig. 1. The potential VSS, the potential VEE, the potential PWC1, the potential PWC2, and the potential CLK1 correspond to the potential VH or the potential VL in the semiconductor device 100 shown in fig. 1.

Specifically, the gate electrode of the transistor 301 is connected to the wiring 319. One of a source terminal and a drain terminal of the transistor 301 is connected to the wiring 317, and the other is connected to one of a source terminal and a drain terminal of the transistor 302. A gate electrode of the transistor 302 is connected to a gate electrode of the transistor 315. The other of the source terminal and the drain terminal of the transistor 302 is connected to a wiring 318. A gate electrode of the transistor 303 is connected to a wiring 320. One of a source terminal and a drain terminal of the transistor 303 is connected to a wiring 317, and the other is connected to a gate electrode of the transistor 302. A gate electrode of the transistor 304 is connected to a wiring 321. One of a source terminal and a drain terminal of the transistor 304 is connected to a wiring 317, and the other is connected to a gate electrode of the transistor 302. A gate electrode of the transistor 305 is connected to a wiring 322. One of a source terminal and a drain terminal of the transistor 305 is connected to a wiring 317, and the other is connected to a gate electrode of the transistor 302. A gate electrode of the transistor 306 is connected to a wiring 319. One of a source terminal and a drain terminal of the transistor 306 is connected to the gate electrode of the transistor 302, and the other is connected to the wiring 318. A gate electrode of the transistor 307 is connected to a wiring 317. One of a source terminal and a drain terminal of the transistor 307 is connected to the other of the source terminal and the drain terminal of the transistor 301, and the other is connected to a gate electrode of the transistor 308. One of a source terminal and a drain terminal of the transistor 308 is connected to a wiring 323 and the other is connected to a wiring 329. A gate electrode of the transistor 309 is connected to a gate electrode of the transistor 302. One of a source terminal and a drain terminal of the transistor 309 is connected to a wiring 329, and the other is connected to a wiring 318. A gate electrode of the transistor 310 is connected to a wiring 317. One of a source terminal and a drain terminal of the transistor 310 is connected to the other of the source terminal and the drain terminal of the transistor 301, and the other is connected to a gate electrode of the transistor 311. One of a source terminal and a drain terminal of the transistor 311 is connected to a wiring 324, and the other is connected to a wiring 328. A gate electrode of the transistor 312 is connected to a gate electrode of the transistor 302. One of a source terminal and a drain terminal of the transistor 312 is connected to a wiring 328, and the other is connected to a wiring 318. A gate electrode of the transistor 313 is connected to a wiring 317. One of a source terminal and a drain terminal of the transistor 313 is connected to the other of the source terminal and the drain terminal of the transistor 301, and the other is connected to a gate electrode of the transistor 314. One of a source terminal and a drain terminal of the transistor 314 is connected to a wiring 325, and the other is connected to a wiring 327. One of a source terminal and a drain terminal of the transistor 315 is connected to a wiring 327, and the other is connected to a wiring 326. One electrode of the capacitor element 316 is electrically connected to the gate electrode of the transistor 302, and the other electrode is connected to the wiring 318.

In fig. 4, the other of the source terminal and the drain terminal of the transistor 315 on the output side is connected to the wiring 326, but the present invention is not limited thereto. The other of the source terminal and the drain terminal of the transistor 315 on the output side may be connected to the wiring 318. However, since the size of the transistor 315 on the output side is large, when the transistor 315 is a normally-on transistor, a leakage current is larger than that of the other transistors. Therefore, when the transistor 315 is a normally-on transistor, if the other of the source terminal and the drain terminal of the transistor 315 is connected to the wiring 318, a phenomenon in which the potential of the wiring 318 is increased by the leakage current and the amplitude of the potential GOUT1 of the output potential is decreased easily occurs. However, when the other of the source terminal and the drain terminal of the transistor 315 on the output side is connected to the wiring 326 and is not connected to the wiring 318 as shown in fig. 4, even if the potential of the wiring 326 increases because the transistor 315 is a normally-on transistor, the potential of the wiring 318 for supplying a potential to the gate electrode of the transistor does not have a relationship with the increase in the potential of the wiring 326. Thus, when the potential of the wiring 326 rises due to the leakage current of the transistor 315, the gate voltage of the transistor 315 is close to a threshold voltage of a negative value, and therefore, the transistor 315 can be turned off even if it is a normally-on transistor.

In one embodiment of the present invention, a gate electrode of at least one of the transistor 309, the transistor 312, and the transistor 315 which corresponds to the transistor on the output side and a gate electrode of the transistor 302 are electrically connected to each other through a conductive film different from the gate electrode. By adopting the above-described structure, the area of each conductive film serving as a gate electrode can be suppressed to be small as compared with the case where the gate electrodes of the transistor 309, the transistor 312, the transistor 315, and the transistor 302 are each formed using one conductive film. Therefore, electrostatic damage of the conductive film serving as the gate electrode due to the antenna effect may not be easily generated.

In addition, one embodiment of the present invention is not limited to a structure in which two conductive films serving as gate electrodes are electrically connected to each other through a conductive film different from the two conductive films. For example, two conductive films which can also be used as gate electrodes are electrically connected by a plurality of conductive films different from the two conductive films. In this case, at least one of the plurality of conductive films is formed in a layer different from the two conductive films serving as the gate electrodes.

In addition, one embodiment of the present invention is not limited to a structure in which an insulating film is provided between a plurality of conductive films serving as gate electrodes and a conductive film for electrically connecting the plurality of conductive films. In one embodiment of the present invention, a plurality of conductive films which function as gate electrodes and a conductive film which electrically connects the plurality of conductive films can be manufactured in different steps. In this case, an insulating film may not be formed between the plurality of conductive films serving as the gate electrodes and the conductive film for electrically connecting the plurality of conductive films.

Embodiment mode 2

In this embodiment, a shift register in which a plurality of stages of the pulse generating circuits 300 shown in fig. 4 are connected will be described.

The shift register shown in fig. 5 includes pulse generation circuits 300_1 to 300_ y (y is a natural number) and a dummy pulse generation circuit 300_ d. The pulse generation circuits 300_1 to 300_ y have the same structures as those of the pulse generation circuit 300 shown in fig. 4, respectively. Further, the structure of the pulse generating circuit 300_ d is different from the structure of the pulse generating circuit 300 shown in fig. 4 in that it is not connected to the wiring 322 to which the potential RIN is supplied and the transistor 305 is not provided.

Fig. 7 schematically shows positions of wirings 319 to 325 and wirings 327 to 329 which are connected to the pulse generating circuit 300_ j (j is a natural number of y or less) in the shift register shown in fig. 5. As is apparent from fig. 5 and 7, the potential SROUTj-1 output from the wiring 329 of the pulse generating circuit 300_ j-1 at the previous stage is supplied to the wiring 319 of the pulse generating circuit 300_ j as the potential LIN. However, the potential of the start pulse signal GSP is supplied to the wiring 319 of the first-stage pulse generating circuit 300_ 1.

Further, the potential SROUTj +1 output from the wiring 329 of the pulse generation circuit 300_ j +1 at the subsequent stage is supplied as the potential RIN to the wiring 322 connected to the pulse generation circuit 300_ j. However, the SROUTd output from the wiring 329 of the pulse generating circuit 300_ d is supplied as the potential RIN to the wiring 322 of the y-th stage pulse generating circuit 300_ y.

The potentials of any two of the clock signals GCK1 to GCK4 are supplied to the wiring 321 and the wiring 323, respectively. Specifically, in the pulse generating circuit 300_4m +1, the potential of the clock signal GCK1 is supplied as the potential CLK1 to the wiring 323, and the potential of the clock signal GCK2 is supplied as the potential CLK2 to the wiring 321. In the pulse generating circuit 300_4m +2, the potential of the clock signal GCK2 is supplied as the potential CLK1 to the wiring 323, and the potential of the clock signal GCK3 is supplied as the potential CLK2 to the wiring 321. In the pulse generating circuit 300_4m +3, the potential of the clock signal GCK3 is supplied as the potential CLK1 to the wiring 323, and the potential of the clock signal GCK4 is supplied as the potential CLK2 to the wiring 321. In the pulse generating circuit 300_4m +4, the potential of the clock signal GCK4 is supplied as the potential CLK1 to the wiring 323, and the potential of the clock signal GCK1 is supplied as the potential CLK2 to the wiring 321. In the pulse generating circuit 300_ d, the potential of the clock signal GCK1 is supplied as the potential CLK1 to the wiring 323, and the potential of the clock signal GCK2 is supplied as the potential CLK2 to the wiring 321. However, m is an arbitrary integer, which satisfies the condition that the total number of pulse generating circuits 300 is y.

Further, the

wirings

324 and 325 are supplied with potentials of any two of the pulse width control signal PWCA to the pulse width control signal PWCD and the pulse width control signal PWCA to the pulse width control signal PWCD, respectively. Specifically, in the pulse generating circuit 300_4m +1, the potential of the pulse width control signal PWCa is supplied to the wiring 325 as the potential PWC1, and the potential of the pulse width control signal PWCa is supplied to the wiring 324 as the potential PWC 2. In the pulse generating circuit 300_4m +2, the potential of the pulse width control signal PWCb is supplied to the wiring 325 as the potential PWC1, and the potential of the pulse width control signal PWCb is supplied to the wiring 324 as the potential PWC 2. In the pulse generating circuit 300_4m +3, the potential of the pulse width control signal PWCc is supplied as the potential PWC1 to the wiring 325, and the potential of the pulse width control signal PWCc is supplied as the potential PWC2 to the wiring 324. In the pulse generating circuit 300_4m +4, the potential of the pulse width control signal PWCd is supplied to the wiring 325 as the potential PWC1, and the potential of the pulse width control signal PWCd is supplied to the wiring 324 as the potential PWC 2. In the pulse generating circuit 300_ d, the potential of the pulse width control signal PWCa is supplied as the potential PWC1 to the wiring 325, and the potential of the pulse width control signal PWCa is supplied as the potential PWC2 to the wiring 324.

The potential GOUT1 of the wiring 327 connected to the pulse generating circuit 300_ j is supplied to the scanning line GLaj.

The polarity of the potential SROUT _ j of the wiring 329 connected to the pulse generating circuit 300_ j is inverted by the inverter 351_ j and supplied to the scan line GLbj. Specifically, the inverter 351_4m +1 is input with the clock signal GCK2, and when the potential of the clock signal GCK2 is low level, the polarity of the potential SROUT _4m +1 is inverted and supplied to the scan line GLb4m + 1. The inverter 351_4m +2 is input with the clock signal GCK3, and when the potential of the clock signal GCK3 is low level, the polarity of the potential SROUT _4m +2 is inverted and supplied to the scan line GLb4m + 2. The inverter 351_4m +3 is input with the clock signal GCK4, and when the potential of the clock signal GCK4 is low level, the polarity of the potential SROUT _4m +3 is inverted and supplied to the scan line GLb4m + 3. The inverter 351_4m +4 is input with the clock signal GCK1, and when the potential of the clock signal GCK1 is low level, the polarity of the potential SROUT _4m +4 is inverted and supplied to the scan line GLb4m + 4. The inverter 351_ d is input with a clock signal GCK2, and when the potential of the clock signal GCK2 is low level, the polarity of the potential SROUT _ d is inverted and supplied to the scan line GLbd.

Further, the polarity of the potential GOUT2 of the wiring 328 connected to the pulse generating circuit 300_ j is inverted by the inverter 350_ j and supplied to the scan line GLcj. Specifically, the inverter 350_4m +1 is input with the clock signal GCK2, and when the potential of the clock signal GCK2 is low level, the polarity of the potential GOUT2 is inverted and supplied to the scan line GLc4m + 1. The inverter 350_4m +2 is inputted with the clock signal GCK3, and when the potential of the clock signal GCK3 is low level, the polarity of the potential GOUT2 is inverted and supplied to the scan line GLc4m + 2. The inverter 350_4m +3 is inputted with the clock signal GCK4, and when the potential of the clock signal GCK4 is low level, the polarity of the potential GOUT2 is inverted and supplied to the scan line GLc4m + 3. The inverter 350_4m +4 is inputted with the clock signal GCK1, and when the potential of the clock signal GCK1 is low level, the polarity of the potential GOUT2 is inverted and supplied to the scan line GLc4m + 4. The inverter 350_ d is input with a clock signal GCK2, and inverts the polarity of the potential GOUT2 to be supplied to the scan line GLcd when the potential of the clock signal GCK2 is low level.

Next, the operation of the pulse generating circuit 300 shown in fig. 4 will be described with reference to the timing chart shown in fig. 6. In all the periods, the potential INRES is always at a low level.

As shown in fig. 6, in the period t1, the potential CLK1 supplied to the wiring 323 is low level, the potential CLK2 supplied to the wiring 321 is low level, the potential of the pulse-width control signal PWC1 supplied to the wiring 325 is low level, the potential of the pulse-width control signal PWC2 supplied to the wiring 324 is low level, the potential LIN supplied to the wiring 319 is high level, and the potential RIN supplied to the wiring 322 is low level.

Therefore, in the period t1, the potential (low level) of the pulse width control signal PWC1 supplied to the wiring 325 in the pulse generating circuit 300 is supplied to the wiring 327 as the potential GOUT 1. Further, the potential (low level) of the pulse width control signal PWC2 supplied to the wiring 324 is supplied to the wiring 328 as a potential GOUT 2. Further, the potential CLK1 (low level) supplied to the wiring 323 is supplied to the wiring 329 as a potential SROUT.

Next, as shown in fig. 6, in the period t2, the potential CLK1 supplied to the wiring 323 is high level, the potential CLK2 supplied to the wiring 321 is low level, the potential of the pulse-width control signal PWC1 supplied to the wiring 325 changes from low level to high level, the potential of the pulse-width control signal PWC2 supplied to the wiring 324 is low level, the potential LIN supplied to the wiring 319 is high level, and the potential RIN supplied to the wiring 322 is low level.

Therefore, in the period t2, the potential of the pulse width control signal PWC1 supplied to the wiring 325 in the pulse generating circuit 300 (changes from low level to high level) is supplied to the wiring 327 as the potential GOUT 1. Further, the potential (low level) of the pulse width control signal PWC2 supplied to the wiring 324 is supplied to the wiring 328 as a potential GOUT 2. Further, the potential CLK1 (high level) supplied to the wiring 323 is supplied to the wiring 329 as a potential SROUT.

Next, as shown in fig. 6, in the period t3, the potential CLK1 supplied to the wiring 323 is high level, the potential CLK2 supplied to the wiring 321 is low level, the potential of the pulse-width control signal PWC1 supplied to the wiring 325 is high level, the potential of the pulse-width control signal PWC2 supplied to the wiring 324 is high level, the potential LIN supplied to the wiring 319 is changed from high level to low level, and the potential RIN supplied to the wiring 322 is low level.

Therefore, in the period t3, the potential (high level) of the pulse width control signal PWC1 supplied to the wiring 325 in the pulse generating circuit 300 is supplied to the wiring 327 as the potential GOUT 1. Further, the potential (high level) of the pulse width control signal PWC2 supplied to the wiring 324 is supplied to the wiring 328 as a potential GOUT 2. Further, the potential CLK1 (high level) supplied to the wiring 323 is supplied to the wiring 329 as a potential SROUT.

Next, as shown in fig. 6, in the period t4, the potential CLK1 supplied to the wiring 323 is high level, the potential CLK2 supplied to the wiring 321 is low level, the potential of the pulse-width control signal PWC1 supplied to the wiring 325 changes from high level to low level, the potential of the pulse-width control signal PWC2 supplied to the wiring 324 is high level, the potential LIN supplied to the wiring 319 is low level, and the potential RIN supplied to the wiring 322 is low level.

Therefore, in the period t4, the potential of the pulse width control signal PWC1 supplied to the wiring 325 in the pulse generating circuit 300 (changes from high level to low level) is supplied to the wiring 327 as the potential GOUT 1. Further, the potential (high level) of the pulse width control signal PWC2 supplied to the wiring 324 is supplied to the wiring 328 as a potential GOUT 2. Further, the potential CLK1 (high level) supplied to the wiring 323 is supplied to the wiring 329 as a potential SROUT.

Next, as shown in fig. 6, in the period t5, the potential CLK1 supplied to the wiring 323 is low level, the potential CLK2 supplied to the wiring 321 is high level, the potential of the pulse-width control signal PWC1 supplied to the wiring 325 is low level, the potential of the pulse-width control signal PWC2 supplied to the wiring 324 is low level, the potential LIN supplied to the wiring 319 is low level, and the potential RIN supplied to the wiring 322 is high level.

Therefore, in the period t5, the potential VEE (low level) supplied to the wiring 326 in the pulse generating circuit 300 is supplied to the wiring 327 as the potential GOUT 1. Further, the potential VSS (low level) supplied to the wiring 318 is supplied to the wiring 328 as a potential GOUT 2. Further, the potential VSS (low level) supplied to the wiring 318 is supplied to the wiring 329 as a potential SROUT.

In one embodiment of the present invention, as described in embodiment 1, a gate electrode of at least one of the transistor 309, the transistor 312, and the transistor 315 which corresponds to a transistor on the output side and a gate electrode of the transistor 302 are electrically connected to each other through a conductive film different from the gate electrode. By adopting the above-described structure, the area of each conductive film serving as a gate electrode can be suppressed to be small as compared with the case where all gate electrodes of the transistor 309, the transistor 312, the transistor 315, and the transistor 302 are formed of one conductive film. Therefore, electrostatic damage of the conductive film serving as the gate electrode due to the antenna effect may not be easily generated. Thus, in the semiconductor device according to one embodiment of the present invention using the shift register, a reduction in yield due to electrostatic breakdown is less likely to occur.

This embodiment can be implemented in appropriate combination with other embodiments.

Embodiment 3

A configuration example of a pulse generating circuit included in a semiconductor device according to one embodiment of the present invention will be described.

The pulse generation circuit 400 shown in fig. 8A includes transistors 402 to 404 and transistors 415 to 420. By connecting the pulse generation circuits 400 of a plurality of stages, a shift register can be configured.

In the transistor 402, a gate electrode is connected to gate electrodes of the transistor 403 and the transistor 404, one of a source terminal and a drain terminal is connected to the wiring 406, and the other is connected to a gate electrode of the transistor 420. In the transistor 403, one of a source terminal and a drain terminal is connected to the wiring 406, and the other is connected to the wiring 414. In the transistor 404, one of a source terminal and a drain terminal is connected to a wiring 407, and the other is connected to a wiring 413.

In the transistor 415, a gate electrode is connected to the wiring 408, one of a source terminal and a drain terminal is connected to a gate electrode of the transistor 420, and the other is connected to the wiring 405. In the transistor 416, a gate electrode is connected to the wiring 409, one of a source terminal and a drain terminal is connected to gate electrodes of the transistor 402, the transistor 403, and the transistor 404, and the other is connected to the wiring 405. In the transistor 417, a gate electrode is connected to the wiring 410, one of a source terminal and a drain terminal is connected to gate electrodes of the transistor 402, the transistor 403, and the transistor 404, and the other is connected to the wiring 405. In the transistor 418, a gate electrode is connected to the wiring 408, one of a source terminal and a drain terminal is connected to the wiring 406, and the other is connected to gate electrodes of the transistor 402, the transistor 403, and the transistor 404. In the transistor 419, a gate electrode is connected to a gate electrode of the transistor 420, one of a source terminal and a drain terminal is connected to the wiring 414, and the other is connected to the wiring 411. In the transistor 420, one of a source terminal and a drain terminal is connected to the wiring 413, and the other is connected to the wiring 412.

When the transistors 402 to 404 and the transistors 415 to 420 are of an n-channel type, specifically, the potential VDD is supplied to the wiring 405, the potential VSS is supplied to the wiring 406, and the potential VEE is supplied to the wiring 407. Further, potentials of various signals such as a clock signal are supplied to the wirings 408 to 412. Then, the potential GOUT is output from the wiring 413, and the potential SROUT is output from the wiring 414.

In one embodiment of the present invention, a gate electrode of at least one of the transistor 403 and the transistor 404 which corresponds to a transistor on the output side and a gate electrode of the transistor 402 are electrically connected to each other through a conductive film provided in a layer different from the gate electrode. By adopting the above-described structure, the area of each conductive film serving as a gate electrode can be suppressed to be small as compared with the case where all the gate electrodes of the transistor 403, the transistor 404, and the transistor 402 are formed of one conductive film. Therefore, electrostatic damage of the conductive film serving as the gate electrode due to the antenna effect may not be easily generated. This makes it possible to prevent a reduction in yield due to electrostatic breakdown in a semiconductor device according to an embodiment of the present invention in which the pulse generation circuit 400 is used for a shift register or the like.

Alternatively, in one embodiment of the present invention, the gate electrode of the transistor 420 and the gate electrode of the transistor 419 which correspond to the transistors on the output side may be electrically connected to each other through a conductive film provided in a layer different from the gate electrode. With the above configuration, it is possible to prevent a reduction in yield due to electrostatic breakdown in a semiconductor device according to an embodiment of the present invention in which the pulse generation circuit 400 is used for a shift register or the like.

In fig. 8A, one of a source terminal and a drain terminal of the transistor 404 on the output side is connected to the wiring 407, but the present invention is not limited thereto. One of a source terminal and a drain terminal of the transistor 404 on the output side may be connected to the wiring 406. However, as shown in fig. 8A, when one of the source terminal and the drain terminal of the transistor 404 on the output side is connected to the wiring 407 but not to the wiring 406, even if the transistor 404 is a normally-on transistor, the transistor 404 can be turned off when necessary.

The pulse generation circuit 430 shown in fig. 8B includes transistors 432 to 434 and transistors 446 to 452. By connecting the pulse generating circuits 430 of a plurality of stages, a shift register can be configured.

In the transistor 432, a gate electrode is connected to gate electrodes of the transistor 433 and the transistor 434, one of a source terminal and a drain terminal is connected to the wiring 436, and the other is connected to gate electrodes of the transistor 451 and the transistor 452. In the transistor 433, one of a source terminal and a drain terminal is connected to a wiring 436, and the other is connected to a wiring 445. In the transistor 434, one of a source terminal and a drain terminal is connected to a wiring 437, and the other is connected to a wiring 444.

In the transistor 446, a gate electrode is connected to the wiring 438, one of a source terminal and a drain terminal is connected to the gate electrodes of the transistor 451 and the transistor 452, and the other is connected to the wiring 435. In the transistor 447, a gate electrode is connected to the wiring 439, one of a source terminal and a drain terminal is connected to the gate electrodes of the transistor 432, the transistor 433, and the transistor 434, and the other is connected to the wiring 435. In the transistor 448, a gate electrode is connected to the wiring 440, one of a source terminal and a drain terminal is connected to gate electrodes of the transistor 432, the transistor 433, and the transistor 434, and the other is connected to the wiring 435. In the transistor 449, a gate electrode is connected to the wiring 438, one of a source terminal and a drain terminal is connected to the wiring 436, and the other is connected to gate electrodes of the

transistors

432, 433, and 434. In the transistor 450, a gate electrode is connected to a wiring 441, one of a source terminal and a drain terminal is connected to gate electrodes of the transistor 432, the transistor 433, and the transistor 434, and the other is connected to a wiring 435. In the transistor 451, one of a source terminal and a drain terminal is connected to the wiring 445, and the other is connected to the wiring 442. In the transistor 452, one of a source terminal and a drain terminal is connected to the wiring 444, and the other is connected to the wiring 443.

When the transistors 432 to 434 and the transistors 446 to 452 are of an n-channel type, specifically, the potential VDD is supplied to the wiring 435, the potential VSS is supplied to the wiring 436, and the potential VEE is supplied to the wiring 437. Further, potentials of various signals such as a clock signal are supplied to the wirings 438 to 443. Further, a potential GOUT is output from the wiring 444, and a potential SROUT is output from the wiring 445.

In one embodiment of the present invention, a gate electrode of at least one of the transistor 433 and the transistor 434 which corresponds to a transistor on the output side and a gate electrode of the transistor 432 are electrically connected to each other through a conductive film provided in a layer different from the gate electrode. By adopting the above-described structure, the area of each conductive film serving as a gate electrode can be suppressed to be small as compared with the case where all the gate electrodes of the transistor 433, the transistor 434, and the transistor 432 are formed of one conductive film. Therefore, electrostatic damage of the conductive film serving as the gate electrode due to the antenna effect may not be easily generated. This makes it possible to prevent a reduction in yield due to electrostatic breakdown in a semiconductor device according to an embodiment of the present invention in which the pulse generating circuit 430 is used for a shift register or the like.

Alternatively, in one embodiment of the present invention, the gate electrode of the transistor 452 and the gate electrode of the transistor 451 which correspond to the transistors on the output side may be electrically connected to each other through a conductive film provided in a layer different from the gate electrode. With the above configuration, it is possible to prevent a reduction in yield due to electrostatic breakdown in a semiconductor device according to an embodiment of the present invention in which the pulse generating circuit 430 is used for a shift register or the like.

In fig. 8B, one of a source terminal and a drain terminal of the transistor 434 on the output side is connected to the wiring 437, but the present invention is not limited thereto. One of a source terminal and a drain terminal of the transistor 434 on the output side may be connected to the wiring 436. However, as shown in fig. 8B, when one of the source terminal and the drain terminal of the transistor 434 on the output side is connected to the wiring 437 and not to the wiring 436, even if the transistor 434 is a normally-on transistor, the transistor 434 can be turned off when it is necessary to turn it off.

The pulse generating circuit 460 shown in fig. 9A includes transistors 462 to 464 and transistors 476 to 482. By connecting the pulse generating circuits 460 of a plurality of stages, a shift register can be configured.

In the transistor 462, a gate electrode is connected to gate electrodes of the transistor 463 and the transistor 464, one of a source terminal and a drain terminal is connected to the wiring 466, and the other is connected to one of a source terminal and a drain terminal of the transistor 477. In the transistor 463, one of a source terminal and a drain terminal is connected to a wiring 466, and the other is connected to a wiring 475. In the transistor 464, one of a source terminal and a drain terminal is connected to a wiring 467, and the other is connected to a wiring 474.

In the transistor 476, the gate electrode is connected to the wiring 468, one of a source terminal and a drain terminal is connected to one of a source terminal and a drain terminal of the transistor 477, and the other is connected to the wiring 465. In the transistor 477, a gate electrode is connected to the wiring 465, and the other of a source terminal and a drain terminal is connected to gate electrodes of the transistor 481 and the transistor 482. In the transistor 478, a gate electrode is connected to the wiring 469, one of a source terminal and a drain terminal is connected to gate electrodes of the transistor 462, the transistor 463, and the transistor 464, and the other is connected to the wiring 465. In the transistor 479, a gate electrode is connected to a wiring 468, one of a source terminal and a drain terminal is connected to a wiring 466, and the other is connected to a gate electrode of the transistor 462 or the transistor 463, and a gate electrode of the transistor 464. In the transistor 480, a gate electrode is connected to a wiring 470, one of a source terminal and a drain terminal is connected to the transistor 462, the transistor 463, and the transistor 464, and the other is connected to the wiring 465. In the transistor 481, one of a source terminal and a drain terminal is connected to a wiring 475, and the other is connected to a wiring 471. In the transistor 482, one of a source terminal and a drain terminal is connected to the wiring 474, and the other is connected to the wiring 472.

When the transistors 462 to 464 and the transistors 476 to 482 are of an n-channel type, specifically, the potential VDD is supplied to the wiring 465, the potential VSS is supplied to the wiring 466, and the potential VEE is supplied to the wiring 467. Further, potentials of various signals such as a clock signal are supplied to the wirings 468 to 472. Further, a potential GOUT is output from the wiring 474, and a potential SROUT is output from the wiring 475.

In one embodiment of the present invention, a gate electrode of at least one of the transistor 463 and the transistor 464 which corresponds to the transistor on the output side and a gate electrode of the transistor 462 are electrically connected to each other through a conductive film provided in a layer different from the gate electrode. By adopting the above-described structure, the area of each conductive film serving as a gate electrode can be suppressed to be small as compared with the case where all the gate electrodes of the transistor 463, the transistor 464, and the transistor 462 are formed of one conductive film. Therefore, electrostatic damage of the conductive film serving as the gate electrode due to the antenna effect may not be easily generated. This makes it possible to prevent a reduction in yield due to electrostatic breakdown in a semiconductor device according to an embodiment of the present invention in which the pulse generating circuit 460 is used for a shift register or the like.

Alternatively, in one embodiment of the present invention, the gate electrode of the transistor 482 corresponding to the output-side transistor and the gate electrode of the transistor 481 may be electrically connected to each other through a conductive film provided in a layer different from the gate electrode. With the above configuration, it is possible to prevent a reduction in yield due to electrostatic breakdown in a semiconductor device according to an embodiment of the present invention in which the pulse generating circuit 460 is used for a shift register or the like.

In fig. 9A, one of a source terminal and a drain terminal of the transistor 464 on the output side is connected to the wiring 467. One of a source terminal and a drain terminal of the output-side transistor 464 may be connected to the wiring 466. However, as shown in fig. 9A, when one of the source terminal and the drain terminal of the transistor 464 on the output side is connected to the wiring 467 and not connected to the wiring 466, even if the transistor 464 is a normally-on transistor, the transistor 464 can be turned off when necessary.

The pulse generation circuit 500 shown in fig. 9B includes transistors 502 to 504 and transistors 516 to 523. By connecting the pulse generation circuits 500 of a plurality of stages, a shift register can be configured.

In the transistor 502, a gate electrode is connected to gate electrodes of the transistor 503 and the transistor 504, one of a source terminal and a drain terminal is connected to the wiring 506, and the other is connected to one of a source electrode and a drain electrode of the transistor 517. In the transistor 503, one of a source terminal and a drain terminal is connected to a wiring 506, and the other is connected to a wiring 515. In the transistor 504, one of a source terminal and a drain terminal is connected to a wiring 507, and the other is connected to a wiring 514.

In the transistor 516, the gate electrode is connected to the wiring 508, one of a source terminal and a drain terminal is connected to one of a source electrode and a drain electrode of the transistor 517, and the other is connected to the wiring 505. In the transistor 517, a gate electrode is connected to the wiring 505, and the other of a source terminal and a drain terminal is connected to a gate electrode of the transistor 521. In the transistor 518, a gate electrode is connected to the wiring 509, one of a source terminal and a drain terminal is connected to the gate electrodes of the transistor 502, the transistor 503, and the transistor 504, and the other is connected to the wiring 505. In the transistor 519, a gate electrode is connected to the wiring 508, one of a source terminal and a drain terminal is connected to the wiring 506, and the other is connected to gate electrodes of the transistor 502, the transistor 503, and the transistor 504. In the transistor 520, a gate electrode is connected to the wiring 510, one of a source terminal and a drain terminal is connected to the gate electrodes of the transistor 502, the transistor 503, and the transistor 504, and the other is connected to the wiring 505. In the transistor 521, one of a source terminal and a drain terminal is connected to the wiring 515, and the other is connected to the wiring 511. In the transistor 522, a gate electrode is connected to the wiring 505, one of a source terminal and a drain terminal is connected to a gate electrode of the transistor 521, and the other is connected to a gate electrode of the transistor 523. In the transistor 523, one of a source terminal and a drain terminal is connected to the wiring 514, and the other is connected to the wiring 512.

When the transistors 502 to 504 and the transistors 516 to 523 are of an n-channel type, specifically, the potential VDD is supplied to the wiring 505, the potential VSS is supplied to the wiring 506, and the potential VEE is supplied to the wiring 507. Further, potentials of various signals such as a clock signal are supplied to the wirings 508 to 512. Then, the potential GOUT is output from the wiring 514, and the potential SROUT is output from the wiring 515.

In one embodiment of the present invention, a gate electrode of at least one of the transistor 503 and the transistor 504 which corresponds to the transistor on the output side and a gate electrode of the transistor 502 are electrically connected to each other through a conductive film provided in a layer different from the gate electrode. By adopting the above-described structure, the area of each conductive film serving as a gate electrode can be suppressed to be small as compared with the case where all the gate electrodes of the transistor 503, the transistor 504, and the transistor 502 are formed of one conductive film. Therefore, electrostatic damage of the conductive film serving as the gate electrode due to the antenna effect may not be easily generated. This makes it possible to prevent a reduction in yield due to electrostatic breakdown in a semiconductor device according to an embodiment of the present invention in which the pulse generating circuit 500 is used for a shift register or the like.

In fig. 9B, one of a source terminal and a drain terminal of the transistor 504 on the output side is connected to the wiring 507, but the present invention is not limited thereto. One of a source terminal and a drain terminal of the transistor 504 on the output side may be connected to the wiring 506. However, as shown in fig. 9B, when one of the source terminal and the drain terminal of the transistor 504 on the output side is connected to the wiring 507 and not to the wiring 506, even if the transistor 504 is a normally-on transistor, the transistor 504 can be turned off when it is necessary to turn it off.

The pulse generating circuit 530 shown in fig. 10 includes transistors 532 to 534 and transistors 546 to 553. By connecting the pulse generation circuits 530 of the plurality of stages, a shift register can be configured.

In the transistor 532, a gate electrode is connected to gate electrodes of the transistor 533 and the transistor 534, one of a source terminal and a drain terminal is connected to the wiring 536, and the other is connected to one of a source electrode and a drain electrode of the transistor 552. In the transistor 533, one of a source terminal and a drain terminal is connected to the wiring 536, and the other is connected to the wiring 545. In the transistor 534, one of a source terminal and a drain terminal is connected to a wiring 537, and the other is connected to a wiring 544.

In the transistor 546, the gate electrode is connected to the wiring 538, one of the source terminal and the drain terminal is connected to one of the source electrode and the drain electrode of the transistor 532, and the other is connected to the wiring 535. In the transistor 547, a gate electrode is connected to a wiring 539, one of a source terminal and a drain terminal is connected to gate electrodes of the transistor 532, the transistor 533, and the transistor 534, and the other is connected to a wiring 535. In the transistor 548, a gate electrode is connected to the wiring 540, one of a source terminal and a drain terminal is connected to gate electrodes of the

transistors

532, 533, and 534, and the other is connected to the wiring 535. In the transistor 549, a gate electrode is connected to the wiring 538, one of a source terminal and a drain terminal is connected to the wiring 536, and the other is connected to gate electrodes of the transistor 532, the transistor 533, and the transistor 534. In the transistor 550, a gate electrode is connected to the wiring 535, one of a source terminal and a drain terminal is connected to one of a source terminal and a drain terminal of the transistor 552, and the other is connected to a gate electrode of the transistor 551. In the transistor 551, one of a source terminal and a drain terminal is connected to a wiring 545, and the other is connected to a wiring 541. In the transistor 552, a gate electrode is connected to the wiring 535, and the other of a source terminal and a drain terminal is connected to a gate electrode of the transistor 553. In the transistor 553, one of a source terminal and a drain terminal is connected to a wiring 544, and the other is connected to a wiring 542.

When the transistors 532 to 534 and the transistors 546 to 553 are of an n-channel type, specifically, the potential VDD is supplied to the wiring 535, the potential VSS is supplied to the wiring 536, and the potential VEE is supplied to the wiring 537. Further, potentials of various signals such as a clock signal are supplied to the wirings 538 to 542. Further, a potential GOUT is output from the wiring 544, and a potential SROUT is output from the wiring 545.

In one embodiment of the present invention, a gate electrode of at least one of the transistor 533 and the transistor 534 which corresponds to the transistor on the output side and a gate electrode of the transistor 532 are electrically connected to each other through a conductive film provided in a layer different from the gate electrode. By adopting the above-described structure, the area of each conductive film serving as a gate electrode can be suppressed to be small as compared with the case where all the gate electrodes of the

transistors

533, 534, and 532 are formed of one conductive film. Therefore, electrostatic damage of the conductive film serving as the gate electrode due to the antenna effect may not be easily generated. This makes it possible to prevent a reduction in yield due to electrostatic breakdown in a semiconductor device according to an embodiment of the present invention in which the pulse generating circuit 530 is used for a shift register or the like.

In fig. 10, one of a source terminal and a drain terminal of the transistor 534 on the output side is connected to the wiring 537, but the present invention is not limited thereto. One of a source terminal and a drain terminal of the transistor 534 on the output side may be connected to the wiring 536. However, as shown in fig. 10, when one of a source terminal and a drain terminal of the transistor 534 on the output side is connected to the wiring 537 and not to the wiring 536, even if the transistor 534 is a normally-on transistor, the transistor 534 can be turned off when it is necessary to turn it off.

Embodiment 4

A cross-sectional structure of a pixel and a driver circuit of a semiconductor display device according to one embodiment of the present invention will be described with reference to fig. 11, taking a light-emitting device using an OLED as an example. Fig. 11 shows a cross-sectional view of the pixel 840 and the driver circuit 841 as an example.

In fig. 11, a pixel 840 includes a light emitting element 832 and a transistor 831 which controls supply of current to the light emitting element 832. The pixel 840 may include various semiconductor elements such as a transistor which controls an image signal input to the pixel 840, a capacitor which holds a potential of the image signal, or the like in addition to the light-emitting element 832 and the transistor 831 described above.

In addition, in fig. 11, the driver circuit 841 includes a transistor 830. Specifically, the transistor 830 corresponds to a transistor on the output side included in the shift register corresponding to a part of the driver circuit 841. The driver circuit 841 may include various semiconductor elements such as a transistor or a capacitor element in addition to the transistor 830 described above.

The transistor 831 includes a conductive film 816 functioning as a gate electrode, a gate insulating film 802 over the conductive film 816, a semiconductor film 817 provided over the gate insulating film 802 at a position overlapping with the conductive film 816, and a conductive film 815 and a conductive film 818 functioning as a source terminal or a drain terminal over the semiconductor film 817 over the substrate 800 having an insulating surface. The conductive film 816 also functions as a scan line.

The transistor 830 includes a conductive film 812 functioning as a gate electrode, a gate insulating film 802 over the conductive film 812, a semiconductor film 813 provided over the gate insulating film 802 at a position overlapping with the conductive film 812, and a conductive film 814 and a conductive film 819 functioning as a source terminal or a drain terminal over the semiconductor film 813 over a substrate 800 having an insulating surface.

Further, the conductive film 850 provided over the substrate 800 having an insulating surface functions as a gate electrode of a transistor different from the transistor 830. The

conductive films

812 and 850 are connected to the conductive film 851 on the gate insulating film 802 through an opening in the gate insulating film 802 provided on the

conductive films

812 and 850.

Further, an insulating film 820 and an insulating film 821 are sequentially stacked over the conductive film 814, the conductive film 815, the conductive film 818, the conductive film 819, and the conductive film 851. Further, a conductive film 852 and a conductive film 853 are provided over the insulating film 821. The

conductive films

852 and 853 are connected to the

conductive films

851 and 818 through openings provided in the insulating

films

820 and 821, respectively.

An insulating film 854 is provided over the

conductive films

852 and 853. Further, a conductive film 822 functioning as an anode is provided over the insulating film 854. The conductive film 822 is connected to the conductive film 853 through an opening formed in the insulating film 854.

An insulating film 824 having an opening portion which exposes part of the conductive film 822 is provided over the insulating film 854. An EL layer 825 and a conductive film 826 functioning as a cathode are stacked in this order over part of the conductive film 822 and the insulating film 854. A region where the conductive film 822, the EL layer 825, and the conductive film 826 overlap corresponds to the light-emitting element 832.

In addition, in one embodiment of the present invention, in the transistor 830 and the transistor 831, a semiconductor such as amorphous, microcrystalline, polycrystalline, or single-crystal silicon or germanium or the like can be used for the semiconductor film, or a wide bandgap semiconductor such as an oxide semiconductor can be used for the semiconductor film.

When a semiconductor such as amorphous, microcrystalline, polycrystalline, or single crystalline silicon or germanium is used for the semiconductor films of the transistor 830 and the transistor 831, an impurity element imparting one conductivity is added to the semiconductor films to form an impurity region serving as a source region or a drain region. For example, by adding phosphorus or arsenic to the semiconductor film, an impurity region having n-type conductivity can be formed. Further, for example, by adding boron to the semiconductor film, an impurity region having p-type conductivity can be formed.

When an oxide semiconductor is used for the semiconductor films of the

transistors

830 and 831, an impurity region serving as a source region or a drain region may be formed by adding a dopant to the semiconductor films. As the dopant, an ion implantation method can be used. As dopants, for example, it is possible to use: rare gases such as helium, argon, and xenon; or an element of group 15 of the periodic table such as nitrogen, phosphorus, arsenic, antimony, etc. For example, when nitrogen is used as a dopant, the concentration of nitrogen atoms in the impurity region is preferably 5 × 10¹⁹/cm³Above and 1 × 10²²/cm³The following.

In addition, as the silicon semiconductor, there can be used: amorphous silicon produced by a vapor deposition method such as a plasma CVD method or a sputtering method; polycrystalline silicon in which amorphous silicon is crystallized by a laser annealing method or the like; and single crystal silicon in which a surface layer is partially peeled off by implanting hydrogen ions or the like into the single crystal silicon wafer.

In addition, the oxide semiconductor preferably contains at least indium (In) or zinc (Zn). In and Zn are particularly preferably contained. In addition, it is preferable to have gallium (Ga) as a stabilizer (stabilizer) for reducing unevenness of electrical characteristics of a transistor using the above oxide in addition to the above elements. Further, tin (Sn) is preferably contained as the stabilizer. Further, hafnium (Hf) is preferably contained as the stabilizer. Further, aluminum (Al) is preferably contained as the stabilizer.

As other stabilizers, one or more of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), which are lanthanoids, may be contained.

For example, as the oxide semiconductor, there can be used: indium oxide, tin oxide, zinc oxide; In-Zn-based oxides, Sn-Zn-based oxides, Al-Zn-based oxides, Zn-Mg-based oxides, Sn-Mg-based oxides, In-Ga-based oxides of binary metal oxides; In-Ga-Zn based oxide (also referred to as IGZO) of ternary metal oxide, In-Al-Zn based oxide, In-Sn-Zn based oxide, Sn-Ga-Zn based oxide, Al-Ga-Zn based oxide, Sn-Al-Zn based oxide, In-Hf-Zn based oxide, In-La-Zn based oxide, In-Ce-Zn based oxide, In-Pr-Zn based oxide, In-Nd-Zn based oxide, In-Sm-Zn based oxide, In-Eu-Zn based oxide, In-Gd-Zn based oxide, In-Tb-Zn based oxide, In-Dy-Zn based oxide, In-Ho-Zn based oxide, In-Er-Zn based oxide, and the like, An In-Tm-Zn oxide, an In-Yb-Zn oxide, and an In-Lu-Zn oxide; In-Sn-Ga-Zn based oxide, In-Hf-Ga-Zn based oxide, In-Al-Ga-Zn based oxide, In-Sn-Al-Zn based oxide, In-Sn-Hf-Zn based oxide, In-Hf-Al-Zn based oxide of quaternary metal oxide. In addition, the oxide semiconductor may contain silicon.

For example, the In-Ga-Zn based oxide refers to an oxide containing In, Ga, and Zn, and the ratio of In, Ga, and Zn is not limited. In addition, metal elements other than In, Ga, and Zn may be contained. In addition, an In-Ga-Zn based oxide semiconductor has sufficiently high resistance In the absence of an electric field, can sufficiently reduce off-current, and has high mobility, and therefore is suitable as a semiconductor material for a semiconductor device.

For example, In: ga: 1, Zn: 1: 1 (1/3: 1/3: 1/3) or In: ga: zn is 2: 2: an In-Ga-Zn-based oxide having an atomic ratio of 1(═ 2/5: 2/5: 1/5) or an oxide In the vicinity of the composition. Alternatively, it is preferable to use In: sn: 1, Zn: 1: 1 (1/3: 1/3: 1/3), In: sn: zn is 2: 1: 3 (1/3: 1/6: 1/2) or In: sn: zn is 2: 1: an In-Sn-Zn-based oxide having an atomic ratio of 5(═ 1/4: 1/8: 5/8) or an oxide In the vicinity of the composition.

For example, In-Sn-Zn based oxides are relatively easy to obtain high mobility. However, even when an In-Ga-Zn based oxide is used, the mobility can be improved by reducing the defect density In the bulk.

Further, an oxide semiconductor which is highly purified by reducing impurities such as moisture and hydrogen which become electron donors (donors) and reducing oxygen deficiency is i-type (intrinsic semiconductor) or infinity i-type. Therefore, a transistor using the above oxide semiconductor has a characteristic that off-current is significantly low. The band gap of the oxide semiconductor is 2eV or more, preferably 2.5eV or more, and more preferably 3eV or more. By using an oxide semiconductor film which is sufficiently reduced in impurity concentration such as moisture or hydrogen and is highly purified by reducing oxygen deficiency, off-current of a transistor can be reduced.

Specifically, it can be confirmed from various experiments that the off current of a transistor in which an oxide semiconductor with high purity is used for a semiconductor film is low. For example, the channel width is 1 × 10⁶The element having a channel length of 10 μm can also obtain an off-current of 1X 10 below the measurement limit of a semiconductor parameter analyzer in a range of 1V to 10V in the voltage (drain voltage) between the source terminal and the drain terminal^-13A is the following characteristic. In this case, it can be seen that: an off-current corresponding to a value obtained by dividing the off-current by a channel width of the transistor is 100zA/μm or less. Further, the off current is measured by using a circuit in which a capacitive element and a transistor are connected and a charge flowing into or out of the capacitive element is controlled by the transistor. In this measurement, an oxide semiconductor film with high purity is used for a channel formation region of the transistor, and an off-current of the transistor is measured from a change in the amount of charge per unit time of the capacitor element. As a result, it was found that: when the voltage between the source terminal and the drain terminal of the transistor is 3V, a lower off-current, i.e., several tens of yA/μm, can be obtained. Thus, the off-current of a transistor in which the oxide semiconductor film with high purity is used for a channel formation region is significantly lower than that of a transistor in which crystalline silicon is used.

In the case where no particular description is given, in an n-channel transistor, the off-current described in the present specification refers to a current that is: when the potential of the gate electrode is 0 or less when the potential of the source terminal is set as a standard in a state where the potential of the drain terminal is set to be higher than the potentials of the source terminal and the gate electrode, a current flows between the source terminal and the drain terminal. Alternatively, in a p-channel transistor, the off-current described in the present specification refers to a current that is: when the potential of the gate electrode is 0 or more when the potential of the source terminal is taken as a standard in a state where the potential of the drain terminal is made lower than the potentials of the source terminal and the gate electrode, a current flows between the source terminal and the drain terminal.

Further, for example, the oxide semiconductor film can be formed by a sputtering method using a target containing In (indium), Ga (gallium), and Zn (zinc). In the case of forming an In — Ga — Zn based oxide semiconductor film by a sputtering method, it is preferable to use a film having an atomic ratio of In: ga: 1, Zn: 1: 1. 4: 2: 3. 3: 1: 2. 1: 1: 2. 2: 1: 3 or 3: 1: 4 In-Ga-Zn based oxide. By forming an oxide semiconductor film using a target of an In-Ga-Zn based oxide having the above atomic ratio, polycrystal or caac (c Axis Aligned crystal) can be easily formed. The relative density of the target material containing In, Ga, and Zn is 90% or more and 100% or less, and preferably 95% or more and less than 100%. By using a target having a high relative density, a dense oxide semiconductor film can be formed.

In addition, when an In — Zn based oxide material is used as the oxide semiconductor, the atomic ratio of the metal elements In the target material used is set to In: zn is 50: 1 to 1: 2 (In terms of molar ratio)₂O₃: ZnO-25: 1 to 1: 4) preferably, In: 20, Zn: 1 to 1: 1 (In terms of molar ratio)₂O₃: ZnO ═ 10: 1 to 1: 2) more preferably, In: 1.5: 1 to 15: 1 (In terms of molar ratio)₂O₃: ZnO ═ 3: 4 to 15: 2). For example, as a target for forming an oxide semiconductor film of an In — Zn based oxide, when the atomic ratio is In: zn: o ═ X: y: when Z is greater than Z>1.5X + Y. By setting the Zn ratio to a value within the above range, the mobility can be improved.

The oxide semiconductor film is in a single crystal, polycrystalline (also referred to as polycrystalline), amorphous, or the like state.

The Oxide Semiconductor film is preferably a CAAC-OS (C Axis Aligned Crystalline Oxide Semiconductor: C-Axis Aligned Crystalline Oxide Semiconductor) film.

The CAAC-OS film is not completely single crystalline nor completely amorphous. The CAAC-OS film is an oxide semiconductor film having a crystal-amorphous mixed phase structure in which a crystal portion and an amorphous portion are present in an amorphous phase. In addition, the size of the crystal part is a size that can be accommodated in a cube having one side of less than 100nm in many cases. In addition, in an image observed with a Transmission Electron Microscope (TEM), the boundary between the amorphous portion and the crystalline portion included in the CAAC-OS film is not clear. In addition, no grain boundary (grain boundary) was observed in the CAAC-OS film by TEM. Therefore, in the CAAC-OS film, the decrease in electron mobility due to the grain boundary is suppressed.

The c-axis of the crystal portion included in the CAAC-OS film is aligned in a direction parallel to a normal vector of a formed surface or a normal vector of a surface of the CAAC-OS film, has a triangular or hexagonal atomic arrangement when viewed from a direction perpendicular to an ab-plane, and metal atoms are arranged in a layer or metal atoms and oxygen atoms are arranged in a layer when viewed from a direction perpendicular to the c-axis. The directions of the a-axis and the b-axis may be different from each other between the different crystal portions. In the present specification, when only "vertical" is described, the range of 85 to 95 inclusive is also included. In addition, when only "parallel" is described, the range of-5 to 5 is also included.

In addition, the distribution of the crystal portion may be uneven in the CAAC-OS film. For example, in the case where crystal growth is performed from the surface side of the oxide semiconductor film in the formation of the CAAC-OS film, the proportion of crystal portions in the vicinity of the surface may be higher than that in the vicinity of the surface to be formed. Further, by adding an impurity to the CAAC-OS film, a crystal portion may be amorphized in the impurity-added region.

Since the c-axis of the crystal portion included in the CAAC-OS film is aligned in a direction parallel to the normal vector of the formed surface or the normal vector of the surface of the CAAC-OS film, the c-axis sometimes faces different directions from each other depending on the shape of the CAAC-OS film (the sectional shape of the formed surface or the sectional shape of the surface). The c-axis direction of the crystal portion is a direction parallel to a normal vector of a surface or a normal vector of a surface to be formed when the CAAC-OS film is formed. The crystal portion is formed by performing crystallization processing such as film formation or heating processing after film formation.

The transistor using the CAAC-OS film can reduce variation in electrical characteristics due to irradiation with visible light or ultraviolet light. Therefore, the transistor has high reliability.

The CAAC-OS film is formed by a sputtering method using, for example, a polycrystalline oxide semiconductor sputtering target. When ions collide with the sputtering target, crystal regions included in the sputtering target are cleaved from the a-b surface, that is, flat or granular sputtered particles having a surface parallel to the a-b surface are sometimes detached. At this time, since the sputtered particles in the form of flat plates reach the substrate while maintaining a crystalline state, a CAAC-OS film can be formed.

In addition, in order to form the CAAC-OS film, the following conditions are preferably applied.

By reducing the contamination of impurities during film formation, the destruction of the crystal state by the impurities can be suppressed. For example, the concentration of impurities (hydrogen, water, carbon dioxide, nitrogen, and the like) present in the film forming chamber can be reduced. In addition, the impurity concentration in the film forming gas can be reduced. Specifically, a film forming gas having a dew point of-80 ℃ or lower, preferably-100 ℃ or lower is used.

Further, by increasing the substrate heating temperature at the time of film formation, migration of the sputtered particles occurs after the sputtered particles reach the substrate. Specifically, the film formation is performed in a state where the substrate heating temperature is set to 100 ℃ or higher and 740 ℃ or lower, preferably 200 ℃ or higher and 500 ℃ or lower. When the substrate heating temperature during film formation is increased, the sputtered particles in the form of flat plates reach the substrate, and migrate over the substrate, whereby the flat surfaces of the sputtered particles adhere to the substrate.

Further, it is preferable to reduce plasma damage during film formation by increasing the oxygen ratio in the film forming gas and optimizing the power. The oxygen content in the film forming gas is set to 30 vol.% or more, preferably 100 vol.%.

In the following, an In-Ga-Zn-O compound target is shown as an example of the sputtering target.

Adding InO_XPowder, GaO_YPowder and ZnO_ZThe powders are mixed at a predetermined molar ratio, subjected to a pressure treatment, and then subjected to a heat treatment at a temperature of 1000 ℃ to 1500 ℃, thereby obtaining a polycrystalline In-Ga-Zn-O compound target material. X, Y and Z are arbitrary positive numbers. Here, InO_XPowder, GaO_YPowder and ZnO_ZThe prescribed molar ratio of the powder is, for example, 2: 2: 1. 8: 4: 3. 3: 1: 1. 1: 1: 1. 4: 2: 3 or 3: 1: 2. the kind of the powder and the mixing molar ratio thereof may be appropriately changed depending on the sputtering target material to be produced.

Embodiment 5

In this embodiment, an example of a panel corresponding to one embodiment of a semiconductor display device will be described. The panel shown in fig. 12 includes a substrate 700, a pixel portion 701 over the substrate 700, a signal line driver circuit 702a, a signal line driver circuit 702b, a scan line driver circuit 703a, and a scan line driver circuit 703 b.

The pixel portion 701 includes a plurality of pixels, and a display element and one or more transistors which control the operation of the display element are provided in each pixel. The scanning line driver circuit 703a and the scanning line driver circuit 703b select pixels included in the pixel portion 701 by supplying a potential to a scanning line connected to each pixel. The signal line driver circuit 702a and the signal line driver circuit 702b control image signals supplied to pixels selected by the scanning line driver circuit 703a and the scanning line driver circuit 703 b.

Fig. 12 illustrates a case where a potential is supplied from both ends of the pixel portion 701 to each scanning line by the scanning line driver circuit 703a and the scanning line driver circuit 703 b. With the above configuration, even if the scanning line is lengthened due to an increase in the size of the pixel portion 701, a potential drop due to a wiring resistance of the scanning line can be prevented from occurring in the pixel portion 701.

Further, the signal line driver circuit 702a and the signal line driver circuit 702b supply image signals to the pixels through the signal lines. In fig. 12, a case where the signal line driver circuit 702a supplies an image signal to the pixels through the odd-numbered signal lines and the signal line driver circuit 702b supplies an image signal to the pixels through the even-numbered signal lines is exemplified.

Fig. 12 illustrates a case where the scan line driver circuit 703a and the scan line driver circuit 703b are formed over the substrate 700 together with the pixel portion 701, and the signal line driver circuit 702a and the signal line driver circuit 702b formed over a chip are mounted over the substrate 700 by a TAB (Tape Automated Bonding) method. The scan line driver circuit 703a and the scan line driver circuit 703b which can be formed over a chip are mounted over the substrate 700, and the signal line driver circuit 702a and the signal line driver circuit 702b can be formed over the substrate 700 together with the pixel portion 701. Further, the method for mounting the chip is not limited to the TAB method. The chip may be mounted on the substrate 700 by an FPC (Flexible Printed Circuit) or the like. Alternatively, a Chip may be mounted On the substrate 700 by a COF (Chip On Film) method.

Since the scanning lines are connected to a plurality of pixels, the scanning line driver circuit 703a and the scanning line driver circuit 703b require high current supply capability. Therefore, it is necessary to increase the size of the transistors on the output side of the pulse output circuits included in the scanning line driver circuit 703a and the scanning line driver circuit 703 b. In particular, since an increase in the number of pixels of the pixel portion 701 or an increase in the area of the pixel portion 701 causes an increase in wiring resistance of scan lines or an increase in load connected to the scan lines, it is necessary to further increase the size of the transistors in order to satisfy higher current supply capability of the scan line driver circuit 703a and the scan line driver circuit 703 b. Further, when the size of the transistor is increased, the area of the conductive film used as the gate electrodes of the plurality of transistors in the scanning line driver circuit 703a and the scanning line driver circuit 703b is increased, and thus electrostatic breakdown of the wiring due to the antenna effect is likely to occur. However, in one embodiment of the present invention, the plurality of gate electrodes are electrically connected to each other through a conductive film provided in a layer different from the gate electrode. Accordingly, the area of each conductive film serving as a gate electrode can be suppressed to be small, and thus even if the number of pixels of the pixel portion 701 is increased or the area of the pixel portion 701 is increased, electrostatic breakdown due to an antenna effect is unlikely to occur.

Note that although the case where the structure according to one embodiment of the present invention is applied to the scan line driver circuit 703a and the scan line driver circuit 703b is described in this embodiment, the structure according to one embodiment of the present invention may be applied to the scan line driver circuit 702a and the scan line driver circuit 702b in one embodiment of the present invention.

Embodiment 6

A semiconductor device according to one embodiment of the present invention can be used for a display device, a personal computer, or an image reproducing device provided with a recording medium (typically, a device which can reproduce the content of a recording medium such as a DVD (Digital Versatile Disc) and has a display for displaying the reproduced image). Examples of electronic devices that can include the semiconductor device according to one embodiment of the present invention include mobile phones, game machines including portable game machines, portable information terminals, electronic book readers, video cameras such as digital cameras, goggle type displays (head mounted displays), navigation systems, audio reproducing devices (car audio systems, digital audio players, and the like), copiers, facsimile machines, printers, multifunction printers, Automated Teller Machines (ATMs), and vending machines. Specific examples of these electronic devices are shown in fig. 13A to 13E.

Fig. 13A is a portable game machine including: a frame body 5001; a frame body 5002; a display portion 5003; a display portion 5004; a microphone 5005; a speaker 5006; an operation key 5007; and stylus 5008, etc. By using the semiconductor device according to one embodiment of the present invention for a driver circuit of a portable game machine, the display portion 5003, or the display portion 5004, a portable game machine with high yield can be provided. Note that although the portable game machine illustrated in fig. 13A includes two

display portions

5003 and 5004, the number of display portions included in the portable game machine is not limited to two.

Fig. 13B is a display device, which includes: a frame 5201; a display portion 5202; and a support 5203. By using the semiconductor display device according to one embodiment of the present invention for a driver circuit of a display device or the display portion 5202, a display device with high yield can be provided. In addition, the display device includes all display devices for information display used for a personal computer, TV broadcast reception, advertisement display, and the like.

Fig. 13C is a notebook personal computer, which includes: a frame 5401; a display portion 5402; a keyboard 5403; and a positioning device 5404, etc. By using the semiconductor display device according to one embodiment of the present invention for a driver circuit of a notebook personal computer or the display portion 5402, the notebook personal computer with high yield can be provided.

Fig. 13D is a portable information terminal including: a first frame body 5601; a second frame body 5602; a first display portion 5603; a second display portion 5604; a connection portion 5605; and an operation key 5606. The first display portion 5603 is provided in the first housing 5601, and the second display portion 5604 is provided in the second housing 5602. The first housing 5601 and the second housing 5602 are connected to each other by a connection portion 5605, and the angle between the first housing 5601 and the second housing 5602 can be changed by the connection portion 5605. The map of the first display portion 5603 may be switched according to the angle between the first housing 5601 and the second housing 5602 formed by the connection portion 5605. Further, a semiconductor display device having a function as a position input device may be used for at least one of the first display portion 5603 and the second display portion 5604. In addition, a function as a position input device can be added by providing a touch panel in the semiconductor display device. Alternatively, a function as a position input device may be added by providing a photoelectric conversion element called a photosensor in a pixel portion of a semiconductor display device. By using the semiconductor device according to one embodiment of the present invention for a driver circuit of a portable information terminal, the first display portion 5603, or the second display portion 5604, a portable information terminal with high yield can be provided.

Fig. 13E is a mobile phone, which includes: a frame 5801; a display portion 5802; a voice input unit 5803; an audio output unit 5804; operation keys 5805; and a light receiving portion 5806. By converting light received by the light receiving section 5806 into an electric signal, an image of the outside can be extracted. By using the semiconductor device according to one embodiment of the present invention for a driver circuit or a display portion 5802 of a mobile phone, a mobile phone with high yield can be provided.

Claims

1. A semiconductor device comprising:

a circuit electrically connected to the first wiring, the circuit including a first transistor and a second transistor,

Wherein, the gate electrode of the first transistor is arranged under the gate insulating film,

Wherein, the source electrode and the drain electrode of the first transistor are arranged on the gate insulating film and are in contact with the gate insulating film,

wherein, the gate electrode of the second transistor is arranged under the gate insulating film,

Wherein, the source electrode and the drain electrode of the second transistor are arranged on the gate insulating film and are in contact with the gate insulating film,

wherein, the gate electrode of the first transistor is electrically connected to the gate electrode of the second transistor through a conductive film,

wherein the conductive film is on and in contact with the gate insulating film,

wherein one of the source electrode and the drain electrode of the first transistor is electrically connected to the first wiring,

wherein the other of the source electrode and the drain electrode of the first transistor is electrically connected to a second wiring,

wherein one of the source electrode and the drain electrode of the second transistor is electrically connected to a third wiring,

Wherein, the potential of the second wiring and the potential of the third wiring are low-level potentials,

wherein the potential of the second wiring is higher than the potential of the third wiring,

wherein the ratio between the channel width of the first transistor and the channel length of the first transistor is greater than the ratio between the channel width of the second transistor and the channel length of the second transistor,

Wherein, the semiconductor film of the first transistor and the semiconductor film of the second transistor respectively include oxide semiconductor or silicon.

2. The semiconductor device of claim 1, wherein the ratio between the channel width of the first transistor and the channel length of the first transistor is the second The ratio between the channel width of the transistor and the channel length of the second transistor is twice or more.

3. The semiconductor device of claim 1, wherein

The semiconductor film of the first transistor and the semiconductor film of the second transistor respectively include the oxide semiconductor, and

The oxide semiconductor includes indium and zinc.

4. A semiconductor device comprising:

substrate; and

Wherein, the source electrode and the drain electrode of the first transistor are arranged on the surface of the substrate and are in contact with the surface of the substrate,

wherein, a gate insulating film is provided on the source electrode and the drain electrode of the first transistor,

Wherein, the gate electrode of the first transistor is arranged on the gate insulating film,

wherein the source electrode and the drain electrode of the second transistor are disposed above and in contact with the surface of the substrate,

wherein, the gate electrode of the second transistor is disposed on the gate insulating film,

wherein, the conductive film is disposed on the surface of the substrate and under the gate insulating film,

5. The semiconductor device of claim 4, wherein the ratio between the channel width of the first transistor and the channel length of the first transistor is the second The ratio between the channel width of the transistor and the channel length of the second transistor is twice or more.

6. The semiconductor device of claim 4, wherein

The oxide semiconductor includes indium and zinc.

7. A semiconductor device comprising:

multiple pixels; and

a shift register electrically connected to the first wiring, the shift register including a first transistor and a second transistor,

wherein the conductive film is on and in contact with the gate insulating film,

8. The semiconductor device of claim 7, wherein the ratio between the channel width of the first transistor and the channel length of the first transistor is the second The ratio between the channel width of the transistor and the channel length of the second transistor is twice or more.

9. The semiconductor device of claim 7, wherein

The oxide semiconductor includes indium and zinc.